Nanostructured polymer-based piezoelectric and triboelectric materials and devices for energy harvesting applications

Abstract

Harvesting energy from ambient mechanical sources in our environment has attracted considerable interest due to its potential to power applications such as ubiquitous wireless sensors and Internet of Things devices. In this context, piezoelectric and/or triboelectric materials offer a relatively simple means of directly converting mechanical energy from ubiquitous ambient vibrating sources into electrical power for microscale/nanoscale device applications. In particular, nanoscale energy harvesters, or nanogenerators, are capable of converting low-level ambient vibrations into electrical energy, thus are vital to the realization of the next generation of self-powered devices. Polymer-based nanogenerators are attractive as they are inherently flexible and robust, making them less prone to mechanical failure which is a key requirement for vibrational energy harvesters. They are also lightweight, easy and cheap to fabricate, lead-free and biocompatible, but in many cases their energy harvesting performance is found lacking in comparison to more commonly studied inorganic materials. Recent advances have been made in developing scalable nanofabrication techniques for flexible and low-cost polymer-based nanogenerators with improved energy conversion efficiency, including the incorporation of high-quality polymer nanowires with enhanced crystallinity, piezoelectric and/or surface charge properties. In this review, we discuss aspects of nanomaterials growth and energy harvester device design, including those involving nanowires of polymers of polyvinylidene fluoride and its co-polymers, nylon-11, and poly-lactic acid for scalable piezoelectric and triboelectric nanogenerator applications, as well as the design and performance of polymer-ceramic nanocomposite nanogenerators. In particular, we highlight the effects of growth parameters, nanoconfinement, self-poling, surface polarization, crystalline phases, and device assembly on the energy harvesting performance of a range of recently reported nanostructured polymer-based materials and devices.

Enhanced Piezoelectricity of Electrospun Polyvinylidene Fluoride Fibers for Energy Harvesting

“… 7 , 16 − 20 One of the most promising techniques is electrospinning combining electrical poling and mechanical stretching to produce a high content of the β-phase in PVDF. This fabrication process is often used in scaffold production for tissue engineering, 21 , 22 energy harvesting, 23 filtration, 24 water collection, 25 production of hydrophobic materials, 26 , 27 and many more. During the electrospinning process, the electric field applied to polymer solution introduces electrical polarization.…”

Bioinspired Multiresonant Acoustic Devices Based on Electrospun Piezoelectric Polymeric Nanofibers

“…This agrees with the view that a higher degree of poling would determine not only higher piezoelectric activity but also enhanced triboelectric performance. 62 , 63 Additionally, aligned fibers would allow a better control of the membranes microstructure, which can be purposely engineered to achieve higher triboelectric conversion (i.e., in PVDF-TrFE-based composites, 64 and PVDF-TrFE-multiwall nanotubes-poly(dimethylsiloxane) heterostructures 65 ), thereby turning particularly useful for miniaturized devices. The smaller displacement values and thus narrow range of resonance frequency obtained in the acoustic sweep tests of the aligned fibers are in agreement with the lower strain and the higher tensile modulus.…”

Aerosol‐Jet Printed Fine‐Featured Triboelectric Sensors for Motion Sensing

“…Metals such as copper and aluminum are relatively easily deposited into thin strips on polymer substrates to form metal‐polymer paired triboelectric generators, and thus these have been widely reported in generators with finely grated structures . Although emphasis has been laid on material selection as being critical in designing triboelectric generators, there have been relatively few studies comparing the performance of different triboelectric materials in grated structure–type generators or sensors. This has been due to lack of a consistent and fast‐prototyping technique for the fabrication of polymer–polymer grated‐structure sliding generators, compared to the more commonly studied metal‐polymer ones.…”